Because of high production costs and the environmental costs associated with recovery, transport, and burning of petroleum derived fuels, significant research and development efforts have been directed to replacement of petroleum derived fuels with fuels derived from biomass. The environmental advantages of the use renewable biomass-derived fuels have long been recognized. Not only does use of biomass-derived fuels reduce demand and reliance on non-renewable petroleum resources, but burning of biomass-derived fuels also releases far fewer noxious pollutants into the air.
The biomass product most widely used to fuel motor vehicles is ethanol, often mixed with gasoline to form "gasohol". Fuel ethanol has been produced commercially for many years by fermentation of cane sugar (sucrose) and of sugars obtained from hydrolysis of the starch and/or cellulose present in a wide variety of biomass feedstocks including, for example, grain, potatoes, cassava and wood pulp. However, the cost of fermentation/ethanol production facilities, coupled with costly energy intensive processes for concentrating ethanol from fermentation broths has diminished the attractiveness of ethanol as a motor fuel.
The present invention enhances the economic viability of substituting renewable resource biomass fuels for hydrocarbon fuels by providing for the direct combustion of biomass derived sugars in internal combustion engines. Thus, in accordance with the invention, an assembly is provided for producing mechanical energy by combustion of a sugar fuel. The assembly includes a combustion chamber and means for fluidizing the sugar fuel. Fluidization of the sugar fuel can be accomplished by melting to form a pumpable sugar melt or by combining the fuel with a fluid carrier. When a fluid carrier is used to fluidize the sugar fuel, the fluid carrier is preferably itself a combustible fluid. Fluidized sugar fuel and an oxidizing agent (generally air or oxygen) are injected either separately or in admixture into a combustion chamber, and the resulting combustible mixture is ignited in the combustion chamber. The heat energy of the combustion gases can be transferred to a working fluid, such as water or steam, via a heat exchanger, or it is recovered as mechanical energy by conventional piston/crankshaft, or turbine assemblies.